Chemistry

Chemical Reactions and Processes

571 Questions

Chemical reactions and processes questions cover the transformation of substances through electrolysis, thermal decomposition, and catalysis. Key areas include identifying gas evolution, balancing chemical equations, and understanding industrial chemical applications. This general chemistry topic is a staple in the science sections of multiple competitive examinations.

Thermal decompositionElectrolysis processGas evolution reactionsHeterogeneous catalystsFuel cell components

Chemical Reactions and Processes Questions

Multiple choice

G on heating at high temperature gives _________ .

A white coloured compound A on heating gives a gas C and a solid residue B. C on reaction with RMgX gives carboxyilic acid. B on reaction with water gives D which on reaction with H2O2 gives E through formation of an intermediate compound. E on reaction with dil. HCl gives F and hydrogen peroxide. F is used for removing ice on the roads. F on reaction with sulfuric acid gives G and an acid.

  1. A

  2. B

  3. C

  4. D

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 G is CaSO4. CaSO4→CaO+SO3 B is CaO.

Multiple choice

A on reaction with ___________ and ____________ H2SO4 produces H2O2 and O2 respectively.

When a metal M is heated in excess of air, it gives two products A and B. A is pale blue in colour. B on reaction with liquid ammonia gives C. B on rection with water produces D. B  dispropotionates to A on heating at 670K.

  1. cold dilute, hot dilute

  2. cold dilute, cold concentrated

  3. cold dilute, hot concentrated

  4. hot dilute, hot concentrated

  5. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 A is Na2O2,which is a peroxide, and this is the right answer.

Multiple choice

D on reaction with chlorine gives _____________ .

A white coloured compound A on heating gives a gas C and a solid residue B. C on reaction with RMgX gives carboxyilic acid. B on reaction with water gives D which on reaction with H2O2 gives E through formation of an intermediate compound. E on reaction with dil. HCl gives F and hydrogen peroxide. F is used for removing ice on the roads. F on reaction with sulfuric acid gives G and an acid.

  1. bleaching powder

  2. glauber's salt

  3. hydrolith

  4. fusion mixture

  5. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 As E on reaction with dilute HCl gives H2O2, so E is a peroxide. F is used for removal of ice on the roads, so F may be NaCl or Ca(Cl)2. As E is a peroxide, so F is Ca(Cl)2. So, E is CaO2. Hence, D is Ca(OH)2 and on reaction with chlorine gives bleaching powder.

Multiple choice

Which of the following properties differentiates metals from non-metals?

  1. Non-metals form halides on reacting with halogens.

  2. Non-metals form oxides.

  3. Non-metals form hydrides on reacting with hydrogen.

  4. Non-metals do not replace hydrogen from acids.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The statement which differentiates metals from non-metals is that non-metals do not replace hydrogen from acids, but metals can do.

Multiple choice

When a copper vessel is exposed to moist air, a green coating is formed on its surface. What chemical compounds are present in that coating?

  1. Magnesium oxide and magnesium hydroxide

  2. Copper oxide and copper hydroxide

  3. Copper hydroxide and copper carbonate

  4. Copper oxide and copper carbonate

  5. Magnesium oxide and copper oxide
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

It is the heavy, metallic and hard tin dioxide (SnO2). It is the major ore of tin. It is colourless when pure, but brown or black when iron impurities are present.

Multiple choice

Name the evolved gas in the given experiment.

In an experiment, a wet rocksil wool is placed at the bottom of a boiling tube, then a magnesium ribbon is inseted into the tube and heated over a burner. We can notice that a colourless gas is given out, which burns with a pop sound.

  1. Sodium hydride

  2. Magnesium hydride

  3. Hydrogen sulphide

  4. Ammonia

  5. Hydrogen
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

All the metals are sonorous as they can produce sound. But mercury and lead are the metals, which are non ductile and non sonorous.

Multiple choice

Which of the following compounds does not react with water or steam to liberate hydrogen?

  1. Carbon

  2. Sodium

  3. Magnesium

  4. Lead

  5. Calcium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All non metals do not react with water to form either metal oxides or metal hydroxides. Whether water is in the form of cold water, hot water or steam, all the non metals will remain unresponsive to the action of water. The reason for this is the typical electronic configuration of non metals. Non metals are electronegative are unable to break the bond between H and O in water. Non metals cannot reduce hydrogen by donating electrons. As carbon is a non metal, it will not react with water or steam.

Multiple choice

Why is sodium metal stored under kerosene?

  1. To prevent its reaction with oxygen

  2. To liberate hydrogen

  3. To prevent its reaction with nitrogen

  4. Because its density is higher than water

  5. To prevent its reaction with hydrogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sodium metal reacts with oxygen at room temperature to form sodium oxide. Sodium also reacts violently with water. It is so active that it is normally stored under a liquid with which it does not react. Kerosene or naphtha liquids are commonly used for this purpose. Hence, sodium is stored under kerosene to prevent its reaction with oxygen, moisture and carbon dioxide.

Multiple choice

Which of the following statements is incorrect about sulphuric acid?

  1. It reacts with Barium chloride and forms white precipitates.

  2. It releases SO2 on heating with copper.

  3. It forms H2 gas on heating with NaCl.

  4. It is used in the extraction of metals.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Statement 3 is incorrect because hydrogen gas does not evolve on reaction with sulphuric acid. The following reaction takes place on reaction between them: NaCl (s) + H2SO4 (l) -------> HCl (g) + NaHSO4 (s)